As a drive control method performed in a case where a steady rest is used in a numerical control (hereinafter, “NC”) device, a method in which whether a workpiece being machined has a length equal to or larger than a predetermined length is determined, and if the workpiece has the predetermined or larger length, the steady rest is positioned to support a flat portion of the workpiece (see, for example, Patent Literature 1) has been proposed. A program command according to ISO (International Organization for Standardization)/EIA (Electronic Industries Alliance) is used as a command directed to a peripheral device such as a tailstock or the steady rest provided in such an NC machine tool.
The commands to the peripheral device according to the ISO/EIA program include a command for moving the position and a command for performing the operation. When the position is to be moved, a move command is issued to a “shaft name” given to a drive motor of the corresponding peripheral device. When a peripheral device is to be operated, a command by means of an auxiliary command (hereinafter, “M code”) is issued.